As a service tech for a carrier dealer I usually tell my customers if they're considering upgrading from a gas furnace to a hybrid system I recommend keeping it simple . A home that's 13 yrs old is more then likely well insulated and duct work is up too date. I'm not a big fan of the new green speed inverter driven heatpumps yet due to the fact there still fairly new and allot of problems have come up from factory issues that are still getting ironed out. I'm more for the 2 speed 25hnb carrier model its been flawless from what I've seen. As far as losing efficiency in colder weather, very rarely will the gas kick on due to the new puron 410a refrigerant that's comes in all new equipment . After a year's time I can look at the customers history of gas furnace usage on the user interface and mostly its only used for defrost operation which usually only last about 3 min at a time. My home is 1800sqft I put in a lower priced system just a single stage compressor and kept it simple I set my heatpump lockout to 20 degrees and even when its down into the 20,s I don't notice a temp difference throught my supplies. Don't get me wrong the inverter driven equipment is definitely the next best thing but sometimes it doesn't pay for the added bells and whistles.
